(a) Field of the Invention
The present invention relates to a golf clubhead of so-called "iron golf club head" and its manufacturing method.
(b) Description of Prior Art
Iron golf clubheads have heretofore been manufactured by forging iron to form a sole part, a face part inclined at predetermined angle to said sole part, a neck part or shaft attaching part hollowed out to fit a shaft therein, which have been polished to a final product. Such clubheads of prior art have been designed to enlarge so-called "sweet area", i.e., ball hitting area of face on which balls are hit at relatively regular angles, which is conventionally attained by means of projecting the back of sole part still toward the back, whereby the center of gravity of clubhead is positioned back to lengthen the distance between said center of gravity and the face part, so that said sweet area is capable of being enlarged. According to such prior art, however, there have been some limits of enlarging said "sweet area".
To overcome such limits, there is proposed one representative of prior art with a composite structure disclosed in U.S. patent application Ser. No. 887735, which utilizes a composite structure of two different balance weight densities to transfer balance weight from the hosel and heel to the ball-impact region of the head. That is, the hosel and a portion of the toe are made of a material of a first weight density, and the sole, backweight, remainder of the toe and a majority of the front surface are made of a second weight density, whereby the weight distribution of said head is the greatest adjacent the center of said front surface.
However, it is desirable that the distance between the center of gravity of the head and the ball-impact face is still elongated to provide such clubheads as have "wider sweet area". And in accordance with said prior art of merely structuring members of different specific gravities, it is impossible to provide a golf clubhead having "ultra wide sweet area".